Investigation of on-site inter-orbital single electron hoppings in general multi-orbital systems

TL;DR

This paper introduces a comprehensive multi-orbital Hubbard model incorporating on-site inter-orbital electron hoppings, revealing their fundamental role and effects on electronic band structures and orbital-selective Mott transitions.

Contribution

It systematically defines and analyzes the on-site inter-orbital single electron hopping within a general multi-orbital Hubbard framework, highlighting its significance and effects.

Findings

On-site inter-orbital hopping is a fundamental interaction.

Including this hopping alters band shapes and reduces orbital differentiation.

It suppresses the orbital-selective Mott transition.

Abstract

A general multi-orbital Hubbard model, which includes on-site inter-orbital electron hoppings, is introduced and studied. It is shown that the on-site inter-orbital single electron hopping is one of the most basic interactions. Two electron spin-flip and pair-hoppings are shown to be correlation effects of higher order than the on-site inter-orbital single hopping. It is shown how the double and higher hopping interactions can be well-defined for arbitrary systems. The two-orbital Hubbard model is studied numerically to demonstrate the influence of the single electron hopping effect, leading to a change of the shape of the bands and a shrinking of the difference between the two bands. Inclusion of the on-site inter-orbital hopping suppresses the so-called orbital-selective Mott transition.